Ploidy Flashcards
1
Q
euploidy
A
- multiples of one complete chromosome compliment
- N, 2N, 3N, 4N
- haploid, diploid, triploid, tetraploid
2
Q
aneuploidy
A
- gain or loss of chromosomes equaling less than one complete complement
- trisomy 13- 47, XX, +13
- monosomy 8- 45, XY, -8
- sex chromosomes
- 45X, 47 XXY
3
Q
nomenclature
A
number of chromosomes, sex chromosomes
4
Q
mosaicism
A
- gain of trisomy if non-disjunction from zygote, or loss of trisomy
- presence of at least 2 different cell lines with at least one clear variation between them
- numerical changes 45, X and 46, XX
- structural change- one cell line with a translocation that doesn’t occur in the other
- mosaicism is acquired, can’t be inherited- because zygote is 1 cell
5
Q
chimera
A
- cells fuse and then keep diving
- vs one cell getting a mutation that is propagated in the organism
6
Q
viable autosomal trisomies
A
- 21,
- patau- 13
- edwards 18
7
Q
down syndrome
A
- multiple system defects
- heart, lung, brain, endocrine system, susceptibility to infectious disease, increased risk of leukemia
- high freq of AD
- more problems may arise as individual ages
8
Q
trisomy 13
A
- punched out scalp
- rocker bottom feet
- polydactyly
9
Q
trisomy 18
A
- grow, but don’t develop
- hand sign
10
Q
klinefelter syndrome
A
- 47, XXY
- 1/1000 male live births
- 50% due to meiosis I error in father
- tall
- interfility
- some female characteristics may develop
- learning deficit possible
11
Q
Turner syndrome
A
45, X
- half have that karyotype
- 15% have deletions or rearrangements of X
- 10 % mosaics- 45X/46,XX or 45X/46XY
- if have XY may be male or female phenotype
- male phenotype usually ok
- female- high probability of problem: increased risk of gonadoblastoma- recommendation to remove gonads
- diagnosis important
- cases can range from mild to severe, prenatal counseling can be difficult
- remove gonads if gonadoblastoma is an issue
- other problems may occur with time
12
Q
XXX female
A
- 1/1000 female live births
- usually due to maternal meiosis I error
- average to tall stature
- learning deficit possible
- some fertility problems possible
13
Q
XYY male
A
- 1/1000 live births
- failure of paternal meiosis
- tall stature
- normal intelligence
- normal fertility
- clinically indistinguishable from 46, XY
14
Q
Turner syndrome issues
A
- growth hormone
- monitor for heart malfunctions
- karyotype to check for Y chromosome
- counseling for probably infertility- donor egg
15
Q
XY female
A
1/ 20,000 live births
- androgen insensitive
- phenotypically normal female with testes
- infertility
16
Q
XX “male”
A
- congenital adrenal hyperplasia
- autosomal recessive condition
- mutation results in overproduction of androgens in female fetus
- in utero exposure causes virulization of fetus
- normal ovaries and internal genitalia
- ambiguous external genitalia
- can be due to CAH in mother or fetus
17
Q
XX male
A
- 1/20,000 live births
- X-Y recombination near pseudoautosomal region
- usually normal, possible klinefelter phenotype
- reciprocal translocation is replaced by Xp material which is transmitted to a child results in a turner female phenotype with and apparent 46, XY karyotype
18
Q
XY gonadal dysgenesis
A
- 46, XY disorder of sex development
- 46, XY complete gonadal dysgenesis
19
Q
46, XY disorder of sex development
A
male or female
- 46, XY karyotype
- ambiguous genitalia with mild to severe penoscrotal hypospadias with or without chordee
- dysgenetic testes
- reduced to no sperm production
- mullerian structures that range from absent to presence of a fully developed uterus and fallopian tubes
20
Q
46, XY complete gonadal dysgenesis
A
- 46 XY karyotype
- normal female external genitalia
- completely underdeveloped streak gonads
- no sperm or egg production
- presence of normal mullerian structures
21
Q
structural abnormalities
A
- deletion
- duplication
- translocation
- inversion
22
Q
balanced
A
- all material is present but rearranged
- some of the material is missing or duplicated
23
Q
deletion
A
- loss of a part of a chromosome
- leads to a partial monosomy
- terminal or interstitial
- loss of one or more genes usually leads to clinical abnormalities
- small deletions may be tolerated with minimal clinical abnormalities
- large deletions typically associated with developmental delay, mental retardation, abnormal features
- size is not as important as which genes and how many are missing
24
Q
wolf-hirschhorn syndrome
A
- 4p deletion
- short stature
- developmental delay
- greek helmut face
25
Q
karen
A
- 11 q deletion
- de novo interstitial
26
Q
duplication
A
- additional copy of a chromosome segment
- partial trisomy
- terminal or interstitial
- cornelia de lange no longer duplication
- 3q29 micro, 7q11.13, 16p11.2, 22q11.2
1q21. 1
27
Q
reciprocal translocation
A
- equal exchange involving two or more chromosomes
- can make balanced or unbalanced
28
Q
balanced translocation
A
- increased risk that another pregnancy will have an unbalanced chromosome complement
- increased risk of infertility or spontaneous fetal loss
- increased risk for an abnormal live born (10% per pregnancy)
- relatively common, 1 in 500
- carriers are usually phenotypically normal
- translocations can be inherited
- other members of the family may have the rearrangement
- can be de novo- if detected prenatally, may not be able to tell if it is balanced or not
29
Q
robertsonian translocation
A
- centromere to centromere involving acrocentric chromosomes
- can cause trisomy
30
Q
inverstion
A
- peri (involving centromere) or para centric
- reversal of a chromosomal segment with respect to normal gene arragement
- need a loop
- para can lead to apparent suppression of recombination
- pericentric need larger circle
- larger inversion means more viable gametes because smaller inversion leads to a greater risk of unbalanced gametes
31
Q
paternity
A
- critical to know who the biological father is
- interpretation of data may reveal that the husband is not the father of the child
- if the data input is false, interpretation may be compromised
